perf(terminal): cap write-flush rate at ~30 fps - #64
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…nt cost Measured 2026-06-12: while a Claude session streams, the renderer's Compositor thread burns 40-60% of a core flushing terminal writes on every animation frame. A 33 ms minimum interval between flushes halves paint work and doubles parse-batch size; worst-case added display latency is one frame (~33 ms), imperceptible for streaming text. The throttle timer reuses buf.timerId so the existing teardown paths (flushTerminalBuffer, destroySession) cancel it unchanged; lastFlushAt is cleaned up in destroySession alongside the write buffer.
This was referenced Jun 12, 2026
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Measurement (2026-06-12, live instance)
While one Claude session streams, the renderer's Compositor thread burns 40-60% of a core — terminal data is batched per-rAF, so every frame with pending output triggers parse + paint at 60 fps.
Change
33 ms minimum interval between flushes (
MIN_FLUSH_INTERVAL_MS), tracked per session inlastFlushAt. When data arrives too soon after a flush, a timer covers the remaining interval before the rAF. The timer reusesbuf.timerIdso the existing teardown (flushTerminalBuffer, destroySession — #55) cancels it with zero new fields;lastFlushAtis cleaned in destroySession.Trade-off
Worst-case +33 ms display latency on streaming text — imperceptible. Keystroke echo is unaffected when idle (first write after ≥33 ms quiet flushes on the next frame as before).
Verification
task checkgreen — 214/214 (4 new tests: throttle window respected, burst coalescing, lastFlushAt cleanup, no late write after destroy). Expected effect: compositor ~50% → ~25% during streams.(Implementation by implementer agent, interrupted by rate-limit mid-run; completed and verified by orchestrator.)